Energy transfer amplification for intrabody devices

Abstract

Apparatus for driving current in a power circuit of a medical device inserted into a body of a subject includes a power transmitter, which is adapted to generate, in a vicinity of the body, an electromagnetic field having a predetermined frequency capable of inductively driving the current in the power circuit. A passive energy transfer amplifier, having a resonant response at the frequency of the electromagnetic field is placed in proximity to the medical device so as to enhance the current driven in the power circuit by the electromagnetic field.

1. Apparatus for use in an invasive medical procedure, comprising:
 a wireless position sensor, which is adapted to be inserted into a body of a subject, the position sensor comprising a power circuit, which is adapted to be driven inductively by a radio-frequency (RF) electromagnetic field so as to provide operating energy to the position sensor; 
 a power transmitter, which is adapted to generate the RF electromagnetic field in a vicinity of the body; and 
 a passive energy transfer amplifier, which is adapted to be placed in proximity to the position sensor so as to enhance inductive driving of the power circuit of the wireless position sensor by the RF electromagnetic field, the position sensor transmitting signals for determining six position and orientation coordinates of the position sensor; and 
 a signal processing unit for receiving signals from the position sensor and determining six position and orientation coordinates of the position sensor. 
 
   
   
     2. The apparatus according to  claim 1 , wherein the power transmitter is adapted to generate the RF electromagnetic field at a predetermined frequency, and wherein the passive energy transfer amplifier has a resonant response at the predetermined frequency. 
   
   
     3. The apparatus according to  claim 2 , wherein the passive energy transfer amplifier comprises a coil and a capacitance, which are coupled so as to define a resonant circuit having the resonant response at the predetermined frequency. 
   
   
     4. The apparatus according to  claim 1 , wherein the passive energy transfer amplifier is adapted to be implanted in the body in proximity to the wireless position sensor. 
   
   
     5. The apparatus according to  claim 4 , wherein the wireless position sensor is for use in association with an orthopedic implant, and wherein the passive energy transfer amplifier is incorporated in the orthopedic implant. 
   
   
     6. The apparatus according to  claim 5 , wherein the implant is a hip joint implant, including a femur head element and an acetabulum element, and wherein the passive energy transfer amplifier comprises a coil, which is integrated in the acetabulum element. 
   
   
     7. The apparatus according to  claim 1 , wherein the passive energy transfer amplifier is adapted to be fixed externally to the body in proximity to an area of the body into which the wireless position sensor is inserted. 
   
   
     8. The apparatus according to  claim 7 , wherein the wireless position sensor is fixed to an invasive probe for insertion into a head of the subject, and wherein the passive energy transfer amplifier is adapted to be fixed to a chest of the subject. 
   
   
     9. The apparatus according to  claim 8 , wherein the wireless position sensor is adapted to provide an indication of location of the probe within the heart. 
   
   
     10. The apparatus according to  claim 1 , wherein the power circuit of the wireless position sensor comprises a coil antenna for receiving the electromagnetic field, and wherein the signal transmitter is coupled to transmit the signal via the coil antenna. 
   
   
     11. The apparatus according to  claim 1 , wherein the position sensor comprises a sensor coil, and wherein the apparatus further comprises one or more field generators, which are adapted to generate energy fields in a vicinity of the medical device, which cause currents to flow in the sensor coil responsively to the position and orientation coordinates of the wireless position sensor. 
   
   
     12. Apparatus for use in an invasive medical procedure, comprising;
 a wireless position sensor, which is adapted to be inserted into a body of a subject, the device comprising a power circuit, which is adapted to be driven inductively by a radio-frequency (RF) electromagnetic field generated by a power transmitter outside the body, so as to provide operating energy to the wireless position sensor; and 
 a passive energy transfer amplifier, which is adapted to be placed in proximity to the wireless position sensor so as to enhance inductive driving of the power circuit of the wireless position sensor by the RF electromagnetic field, the wireless position sensor transmitting signals for determining six position and orientation coordinates of the position sensor; and 
 a signal processing unit for receiving signals from the position sensor and determining six position and orientation coordinates of the position sensor. 
 
   
   
     13. An orthopedic implant, comprising:
 a prosthetic joint comprising first and second joint elements, which are adapted to be implanted in a body of a subject; 
 first and second wireless position sensors, which are respectively fixed to the first and second joint elements so as to transmit position signals indicative of an alignment of the first and second joint elements, each of the position sensors comprising a power circuit, which is adapted to be driven inductively by a radio-frequency (RF) electromagnetic field so as to provide operating energy to the sensors; 
 a power transmitter, which is adapted to generate the RF electromagnetic field in a vicinity of the body; and 
 a passive energy transfer amplifier, which is fixed to at least one of the first and second joint elements so as to enhance inductive driving of the power circuit of the wireless position sensors by the RF electromagnetic field; and 
 a signal processing unit for receiving the position signals and determining six position and orientation coordinates for the first and second wireless position sensor. 
 
   
   
     14. The implant according to  claim 13 , wherein the prosthetic joint comprises a hip joint, and wherein the first and second joint elements comprise a femur head element and an acetabulum element, and wherein the passive energy transfer amplifier is fixed to the acetabulum element. 
   
   
     15. The implant according to  claim 13 , wherein the prosthetic joint comprises a knee joint. 
   
   
     16. Invasive medical apparatus, comprising:
 a catheter, having a distal end, which is adapted to be inserted into a heart of a subject, the catheter comprising a wireless position sensor, fixed adjacent to the distal end of the catheter so as to transmit position signals indicative of a position of the catheter within the heart, the position sensor comprising a power circuit, which is adapted to be driven inductively by a radio-frequency (RF) electromagnetic field so as to provide operating energy to the position sensor; a power transmitter, which is adapted to generate the RF electromagnetic field in a vicinity of the body; and 
 a passive energy transfer amplifier, which is adapted to be placed in a vicinity of the heart so as to enhance inductive driving of the power circuit of the wireless position sensors by the RF electromagnetic field; and 
 a signal processing unit for receiving the position signals and determining six position and orientation coordinates for the wireless position sensor. 
 
   
   
     17. The apparatus according to  claim 16 , wherein the passive energy transfer amplifier is adapted to be placed on a chest of the subject adjacent to the heart. 
   
   
     18. The apparatus according to  claim 16 , wherein the wireless position sensor comprises a sensor coil, and wherein the apparatus further comprises one or more field generators, which are adapted to generate energy fields in a vicinity of the heart, wherein the energy fields cause currents to flow in the sensor coil responsively to the position coordinates of the medical device. 
   
   
     19. The apparatus according to  claim 16 , wherein the catheter further comprises one or more electrodes for sensing electrical activity within the heart.